1. Field of the Invention
The present invention relates to packaging and more particularly to an improved packaging system for opening, loading, closing and sealing bag-like containers at a loading station and for isolating the force applied to a loaded container as it is severed from the remainder of the web along a preformed line of weakness.
2. Prior Art
The referenced Article and Machine Patents relate to the utilization of a packaging web comprising a chain of interconnected bags. The bags are each open on one face. The other face of each bag is connected to a contiguous bag along a preformed line of weakness.
The Article Patent describes a simple mechanism for dispensing, opening and loading the interconnected bags. A coiled web of interconnected bags is positioned on a mandrel in a carton. A blower is coupled to the carton to provide a positive pressure within the carton. The bags are fed, closed end first, through a slot in the carton. As the bags emerge from the carton, they are inflated by a relatively gentle flow of air emitted from the slot due to the positive pressure in the carton. A product is inserted in the inflated bag. The operator then moves the web until the next bag emerges from the carton and inflates, and also separates the loaded bag for a sealing operation.
The Machine Patent describes a machine for dispensing, loading, sealing, and severing the bags in sequential automatic operations. In addition, the machine is adapted to be connected to automatic counting and conveying equipment so that products being packaged are all automatically measured and deposited in the bags as the bags are fed to a load station. The Machine Patent also describes a system for providing an interrupted heat seal line whereby heavily loaded bags are not so weakened during the heat sealing operation that they tear along the sealing line.
These two described systems represent a system which is relatively simple, but slow, and a system which is relatively complex, but fast, for dispensing, loading and sealing bags. The optimized system for any given packager depends on a number of variables such as the size and nature of the products being packaged, the number of packages of any given product or group of products required, and the total number of packages, that is the total packaging rate, of the packager.
In the past, the most commonly used system for dispensing, separating and sealing bag-like containers has been basically manual. A machine similar in appearance to that shown in the Machine Patent has been the most commonly used. With this commercially successful arrangement, a web of bags is mounted on a mandrel within a housing. The web is fed through an exit slot near the top of the housing and then downwardly until an open bag is at a load station near the top of the machine and near the exit slot.
In use, the operator deposits the product to be packaged in the open bag at the load station. The operator then grasps the loaded bag, pulling it downwardly until the next bag is at the load station. The loaded bag is then manually severed and the open end is inserted between the jaws of a heat sealer provided near the base of the housing. The jaws are then actuated to close and effect a sealing of the bag. After a predetermined time interval, when a seal has been effected, the jaws will open allowing the bag to drop into a box or other receptacle beneath the machine.
The referenced parent application describes a novel packaging system for opening, loading, closing and sealing bag-like containers at a loading station. Relatively movable gripper and closure bars clamp a loaded container to isolate the forces applied in separating the loaded container from a web. The container can be heat sealed substantially concurrently with the separation. Alternatively, the loaded containers can be separated from the web without being sealed, or can be sealed without being separated from the web to produce a chain of interconnected loaded bags.
The apparatus described in the referenced parent application includes a heater bar and a sealing bar which are movable toward and away from each other to clamp and heat seal a loaded container. A gripper bar is rigidly mounted above the heater bar. The gripper bar cooperates with the sealer bar to grip the packaging web in regions between the heat seal line and a preformed line of weakness in the web. The gripping bar isolates the heat seal line from forces applied to the web to sever the loaded container from the remainder of the web.
Another apparatus feature described in the referenced application is a tear-off mechanism for severing a loaded container from the remainder of the web serially along a preformed line of weakness from one side of the web to the other. The heater bar, the sealer bar and the gripper bar form part of a tear-off assembly which is pivotally mounted about an axis on one side of the web. The tear-off assembly is power driven to effect a sharp and rapid tear-off movement. This rapid tear-off movement not only serves to rapidly sever the loaded container from the remainder of the web but also serves to reduce the effective force imposed on the heat seal line by the weight of the product being packaged.
The heater bar described in the referenced parent application is a blunt member covered with TEFLON to prevent sticking. A spring biased stripper bar is provided to effect a positive removal of the sealed loaded packages from the heater bar.